1. Field of the Invention
The present invention relates to an inflammable gas detector with prearranged action.
2. Description of the Prior Art
An inflammable gas detector is known from European Pat. No. 82830111.9 consisting of a detecting element in the form of a spiral with close windings and composed of a thin platinum-alloy wire inserted in a resistance bridge circuit, so that a variation of the detector resistance as a function of the density of the gas surrounding it will cause in the bridge circuit an imbalance that enables a system, which sets off an alarm and/or produces an action, to obtain a control signal. U.S. patent application Ser. No. 372,658 filed Apr. 28, 1982 and now abandoned corresponds to European Pat. No. 82830111.9.
Numerous tests have shown that the detecting element employed exhibits a variable sensitivity by varying the operating voltage, the level of said voltage depending upon the type of gas in which the detector is located. More specifically, it has been demonstrated that the DC supply voltage for maximum sensitivity and, therefore, for optimum response of the detector is 2 V for methane gase in a 2% concentration, and 1.6 V for propane-butane gas in a 0.8% concentration, and that the variation of the voltage measured at the terminals of the detector so supplied changing from the condition around it without gas to that with gas in the above-mentioned percentage is 0.2 V.